Common Public Radio Interface (CPRI) is a standard published by a great many enterprises in the telecommunications industry together for standardizing the key interfaces between a Radio Equipment Control (REC) and a Radio Equipment (RE) inside a radio base station. On the basis of CPRI standard, the universality of the interfaces between a baseband unit and a radio frequency unit is improved, and it is advantageous to realize the interconnection of the baseband units and radio frequency units of different manufacturers. An REC is typically connected with REs is via optical fibers or cables in the shape of star, chain or ring and the like to form a network.
In FIG. 1, the REC refers to a near-end equipment, and each RE refers to a remote equipment. The REC and the RE mentioned here are respectively called a Build Baseband Unit (BBU) and Remote Radio Unit (RRU) in some systems. The port of the REC is a master port, the port of the RE which is close to the REC side is a slave port, and the port of the RE which is connected with an inferior RE is a master port.
In the case where equipments are cascaded into a network, the normal operating of a system will be influenced if a fault occurs in a physical link, therefore, alarm information is required to be reported fast and accurately so that a maintainer can treat as soon as possible.
At present, in a radio communication system, an alarm generated by a cascaded remote equipment, especially a bottom link alarm, is typically reported by a centralized report method in which all cascaded remote equipments report bottom link alarm information to a near-end equipment through a physical layer channel (layer L1), and then the near-end equipment processes in a uniform and centralized manner. This centralized report method, although extremely excellent in alarm information report speed, causes a lot of pressure for the near-end equipment to process the alarm information as the amount of the data need to be reported grows increasingly for more and more cascaded remote equipments are supported and alarm information is classified more detailedly. Taking a near-end equipment supportive to 10 ports as an example, if each port supports 16-cascade cascaded equipments at most, then the alarm information the near-end equipment needs to process are totally 320*n, wherein the n is the number of the alarms each port of remote equipment of each cascade needs to report. In this case, a great number of resources are wasted in a 16-cascade alarm information detection and report even in most cases there are only 2 or 3 cascade being used instead of 16 cascade. This undoubtedly severe resource waste is still generally companied with a cost increase.
FIG. 2 shows an existing centralized report solution for cascaded alarms in which the alarms ALARM_S generated by the slave port of each RE and ALARM_M generated by the master port of each RE are respectively reported through corresponding bit position of two control words. Each RE only fills bits the RE is corresponds to and transparently transmits the other bits. Taking 16-cascade which is supported as an example, an REC needs to analyze and process 32 alarm bits.
Besides, cascaded networking is featured in that if a cascaded link is broken or runs unstably, the information of all inferior cascades cannot be reported reliably, and that the problem existing in a superior cascade is generally required to be solved preferentially. In the case of a centralized alarm report, the processing on the correlation of alarms is relatively complicated as an alarm occurring in an inferior cascade is related with those of all the superior cascades, that is, the alarm reported by a cascade may be (pay attention: what is used here is ‘may be’) effective only if there is no alarm occurring in any superior cascade because the alarm on an link error of a physical layer channel cannot be extraordinarily strict in most cases. If an unstable link causes an intermittent alarm in a superior cascade, then, due to the difference in alarm processing time, the more complicated the correlation of alarms is, the more possibly an error alarm occurs in an inferior cascade.
In realizing the disclosure, the inventor finds that the prior art has the following technical problems:
In existing centralized alarm report mode for cascaded devices, a near-end equipment needs to process a large amount of reported alarm information, which causes a resource waste and a high processing complexity on the near-end equipment, besides, as it is complicated to process the correlation of alarms, the probability of an error alarm is relatively high.